Fred Ruhe
Well-known member
Tomonori Tanaka, Yoshitsugu Kobayashi, Kenji Ikuno, Tadahiro Ikeda & Haruo Saegusa, 2020
A Marine Hesperornithiform (Avialae: Ornithuromorpha) from the Maastrichtian of Japan: Implications for the Paleoecological Diversity of the Earliest Diving Birds in the End of the Cretaceous
Cretaceous Research Article 104492 (advance online publication)
doi: https://doi.org/10.1016/j.cretres.2020.104492
https://www.sciencedirect.com/science/article/pii/S0195667120301786
Highlights:
We report a new material of a non-hesperornithid hesperornithiform from the lower Maastrichtian of southwest Japan.
This is the first hesperornithiforms from the Maastrichtian marine deposits in Asia.
Our study reveals that the habitat of Maastrichtian hesperornithiforms was extended to both terrestrial and marine environments in Asian and North American continents.
Abstract:
Asian hesperornithiforms are extremely rare in contrast to North American records; thus, their diversity in Asia during the Cretaceous is unclear. Maastrichtian hesperornithiform materials have been reported from both fluvial and marine deposits in North America but only from fluvial deposits in Asia. Asian hesperornithiforms from Maastrichtian deposits have been considered as freshwater taxa because of their occurrence from fluvial sediments and their histological features. Here, we report the first hesperornithiform record from marine Maastrichtian deposits in Asia. It is represented by an isolated left tibiotarsus from the inter-arc basin deposit of the Kita-ama Formation (lower Maastrichtian), Izumi Group of southwest Japan. It has a shallow tibial incision, fibular crest extending to the mid shaft, and laterally angled lateral articular surface. Although its phylogenetic position within Hesperornithiformes is ambiguous, these characters are similar to non-hesperornithid hesperornithiforms. Unossified proximal and distal epiphyses indicate that this individual was immature. A remarkably thick cortical area of the tibiotarsus suggests that this hesperornithiform was a sea-dwelling bird and that the habitat of this group during the Maastrichtian extended to both terrestrial and marine environments in Asia and North America.
Enjoy,
Fred
A Marine Hesperornithiform (Avialae: Ornithuromorpha) from the Maastrichtian of Japan: Implications for the Paleoecological Diversity of the Earliest Diving Birds in the End of the Cretaceous
Cretaceous Research Article 104492 (advance online publication)
doi: https://doi.org/10.1016/j.cretres.2020.104492
https://www.sciencedirect.com/science/article/pii/S0195667120301786
Highlights:
We report a new material of a non-hesperornithid hesperornithiform from the lower Maastrichtian of southwest Japan.
This is the first hesperornithiforms from the Maastrichtian marine deposits in Asia.
Our study reveals that the habitat of Maastrichtian hesperornithiforms was extended to both terrestrial and marine environments in Asian and North American continents.
Abstract:
Asian hesperornithiforms are extremely rare in contrast to North American records; thus, their diversity in Asia during the Cretaceous is unclear. Maastrichtian hesperornithiform materials have been reported from both fluvial and marine deposits in North America but only from fluvial deposits in Asia. Asian hesperornithiforms from Maastrichtian deposits have been considered as freshwater taxa because of their occurrence from fluvial sediments and their histological features. Here, we report the first hesperornithiform record from marine Maastrichtian deposits in Asia. It is represented by an isolated left tibiotarsus from the inter-arc basin deposit of the Kita-ama Formation (lower Maastrichtian), Izumi Group of southwest Japan. It has a shallow tibial incision, fibular crest extending to the mid shaft, and laterally angled lateral articular surface. Although its phylogenetic position within Hesperornithiformes is ambiguous, these characters are similar to non-hesperornithid hesperornithiforms. Unossified proximal and distal epiphyses indicate that this individual was immature. A remarkably thick cortical area of the tibiotarsus suggests that this hesperornithiform was a sea-dwelling bird and that the habitat of this group during the Maastrichtian extended to both terrestrial and marine environments in Asia and North America.
Enjoy,
Fred
